초록 ▼

An operating strategy for a hybrid electric vehicle (HEV) manages the flow of energy to both supply the motive demand power of the HEV and maintain the charge of the energy storage system (ESS). A controller operates the main power unit (HPU) and ESS and, using an optimal fuel cost strategy, scans a

An operating strategy for a hybrid electric vehicle (HEV) manages the flow of energy to both supply the motive demand power of the HEV and maintain the charge of the energy storage system (ESS). A controller operates the main power unit (HPU) and ESS and, using an optimal fuel cost strategy, scans all possible combinations of power from the HPU and ESS that satisfy the motive demand power. The combination with the lowest fuel cost is selected and the ESS is charged, when possible, using marginal charging; but, if the state of charge of the ESS falls below a certain level, fast charging is invoked. A minimum power threshold strategy can be used rather than the fuel cost strategy. The minimum power threshold strategy determines the optimal compromise of HPU operation and ESS operation to maximize fuel economy by using a motive power threshold below which the HPU is not operated except to recharge the ESS.

대표청구항 ▼

[ What is claimed is:] [1.] An optimal, adaptive method for controlling energy flow in a hybrid electric vehicle (HEV) having a main power unit (HPU) and a supplementary bi-directional energy storage system (ESS) to satisfy power demand for vehicle propulsion and auxiliary systems and to maintain st

[ What is claimed is:] [1.] An optimal, adaptive method for controlling energy flow in a hybrid electric vehicle (HEV) having a main power unit (HPU) and a supplementary bi-directional energy storage system (ESS) to satisfy power demand for vehicle propulsion and auxiliary systems and to maintain state of charge (SOC) of said ESS within a selected range while minimizing fuel consumption, comprising the steps of:making an initial estimate of an equivalent amount of fuel to be associated with energy stored in said ESS;determining motive demand power (MDP) of said vehicle;determining an effective power dependent fuel consumption rate for withdrawal of energy from said ESS using known output characteristics of said ESS and the effective fuel value of the energy stored in said ESS;scanning possible combinations of HPU and ESS output power that satisfy MDP;selecting the combination of HPU and ESS output power providing the lowest fuel cost, said fuel cost being the sum of HPU fuel consumption and effective ESS fuel consumption;determining whether the lowest fuel cost combination requires energy from both the HPU and ESS;satisfying MDP and decrementing the fuel value of ESS energy at a rate proportional to the rate of energy withdrawal when the lowest fuel cost combination requires energy from both the HPU and ESS;determining whether the ESS should be charged;operating the HPU at a power level higher than the power demand chosen so as to minimize the fuel cost of energy delivered to and stored in the ESS and incrementing the fuel value associated with energy stored in the ESS at a rate proportional to the rate of fuel usage of the HPU multiplied by the fraction of HPU output diverted to the ESS when the ESS should be charged; andsatisfying MDP with the lowest fuel cost combination of HPU and ESS energy and decrementing the fuel value of ESS energy at a rate proportional to the rate of energy withdrawal when the ESS should not be charged.